For many years, grocery stores have commonly used refrigerating or freezing storage units of the above-mentioned kind, which are accessible from the top along both sides of the unit to allow for an overview of the contents of the storage unit and for free and unhindered access from the top by the customers and the staff.
The refrigerating or freezing merchandising storage unit may be covered with insulation mats during periods in which the grocery store or a similar store is closed in order to reduce energy consumption when storing the goods in the storage unit.
The use of open refrigerating and freezing merchandising storage unit results in extensive losses of energy and it may therefore be provided with an essentially transparent cover. Several examples of covers are known which may be used during opening hours. Thus, refrigerating and freezing storage units provided with a cover by the manufacturer are known. Alternatively, the cover may be retrofitted onto an existing storage unit.
Known covers for refrigerating and freezing merchandising storage units may be divided into two different types. A sliding lid type and a “lift-up” type.
The sliding lid type is of the kind where a cover in the longitudinal direction of the storage unit is typically divided into an appropriate number of plane plates, typically approx. 62.5 cm of width. The individual plates are arranged in two planes so that they may be displaced in the longitudinal direction of the storage unit over, respectively under each other. Examples hereof are known from EP 0 769 262 A2. The plates are transparent which provides for the possibility of examining the goods in the storage unit without having to open it. However, this design only allows for access to the storage compartment in a maximum of half of the longitudinal direction, which limits access to the goods in the storage unit and makes refilling and cleaning of the storage unit difficult since it cannot be opened in the entire longitudinal direction at the same time.
U.S. Pat. No. 2,793,925 discloses a cover with sliding lids that are arranged in two planes and may be displaced in the transversal direction of the storage unit over, respectively under each other. However, the access to the storage compartment is similarly limited to a maximum of half of the top opening area.
The “lift-up” type is of the kind where a cover in the longitudinal direction of the storage unit is divided into an appropriate number of plates, typically 62.5 cm in width. In the width, the lift-up type is divided into two plane plates hinged to a centre console extending in the longitudinal direction so that the individual parts of the 24-hour cover along the longer side of the storage unit may be lifted up and thereby opened. However, operating this type is difficult for little people such as for example children. In addition, a pumping effect is created during opening and closing so that when opened, warm air from the surroundings is sucked into the storage unit and cool air is pumped out into the surroundings when it is closed. This results in an undesirable energy loss.